Increased Cytotoxicity of Vanadium to CHO-K1 Cells in the Presence of Inorganic Selenium.

Zwolak I - Bull Environ Contam Toxicol (2015)

Bottom Line:
The effect of selenium applied as sodium selenite (Na2SeO3) on the cytotoxicity of vanadyl sulphate (VOSO4) was examined using CHO-K1 cells.Observations performed with a phase-contrast microscope showed most cells to be rounded upon treatment with VOSO4 alone.In turn, a majority of cells co-treated with VOSO4 and 1 μM Na2SeO3 were elongated, and exhibited cytoplasmic vacuolization.

ABSTRACTThe effect of selenium applied as sodium selenite (Na2SeO3) on the cytotoxicity of vanadyl sulphate (VOSO4) was examined using CHO-K1 cells. From the resazurin-based assay, it appears that Na2SeO3 at low doses (0.5 and 1 μM) can enhance 100 μM VOSO4-induced cell damage. The two-way ANOVA analysis revealed that the increased cell damage was a consequence of a synergistic interaction of 0.5 μM Na2SeO3 with VOSO4 and 1 μM Na2SeO3 with VOSO4. Observations performed with a phase-contrast microscope showed most cells to be rounded upon treatment with VOSO4 alone. In turn, a majority of cells co-treated with VOSO4 and 1 μM Na2SeO3 were elongated, and exhibited cytoplasmic vacuolization. These results warn of the potential contribution of inorganic selenium to vanadium-induced toxicity.

Fig1: Cytotoxicity of V (VOSO4) and its combination with Se (Na2SeO3) to CHO-K1 cells as measured with the resazurin assay. The CHO-K1 cells were exposed to 100 μM VOSO4 in combination with Na2SeO3 (0.1, 0.5 or 1 μM) for 48 h and thereafter the cytotoxic effect was assessed with the resazurin test. In this test, the amount of resazurin that was not reduced to resorufin is proportional to the number of injured cells. The absorbance of resazurin in control cells (treated with neither V nor Se) was taken as 100 %. Results are presented as a percentage of control cells and represent mean ± SEM derived from five independent experiments. Differences between means (ANOVA/Dunnett’s T3 test) are indicated by *p < 0.05 significantly lower than control, #p < 0.001 significantly higher than control, ap < 0.05 significantly higher than V alone

Mentions:
The results of the resazurin assay obtained demonstrated that the 48-h exposure of CHO-K1 cells to 100 μM vanadyl alone induced significant (p < 0.05, one-way ANOVA with Dunnett’s T3 test) cytotoxicity compared to the control (cells treated with neither vanadyl nor selenite, Fig. 1). Treatment of cells only with selenite at concentrations of 0.1 and 0.5 μM seemed to slightly decrease cell damage compared to the control cultures, and the viability of cells exposed to 1 μM selenite was similar to the control. The three above-mentioned concentrations of selenite were regarded as non-cytotoxic. Importantly, the review of literature data revealed that cultured mammalian cells substantially differed in their sensitivity to selenite, as described hereafter. For instance, cultured human neuronal cells showed a viability decrease following exposure to selenite at doses as low as 0.1 μM (Maraldi et al. 2011). However, concentrations of selenite comparable to those used in our study were non-toxic to primary rabbit hepatocytes (Müller and Pallauf 2003), human hepatoma (HepG2) cells (Helmy et al. 2000), prostatic (PNT-1) cells (Maraldi et al. 2011), or human HaCaT keratinocytes (Hazane-Puch et al. 2013). Notably, human exposure to inorganic selenium via drinking water at concentrations similar to or much higher than those studied here have been documented in some regions of the world (reviewed by Vinceti et al. 2013a).Fig. 1

Fig1: Cytotoxicity of V (VOSO4) and its combination with Se (Na2SeO3) to CHO-K1 cells as measured with the resazurin assay. The CHO-K1 cells were exposed to 100 μM VOSO4 in combination with Na2SeO3 (0.1, 0.5 or 1 μM) for 48 h and thereafter the cytotoxic effect was assessed with the resazurin test. In this test, the amount of resazurin that was not reduced to resorufin is proportional to the number of injured cells. The absorbance of resazurin in control cells (treated with neither V nor Se) was taken as 100 %. Results are presented as a percentage of control cells and represent mean ± SEM derived from five independent experiments. Differences between means (ANOVA/Dunnett’s T3 test) are indicated by *p < 0.05 significantly lower than control, #p < 0.001 significantly higher than control, ap < 0.05 significantly higher than V alone

Mentions:
The results of the resazurin assay obtained demonstrated that the 48-h exposure of CHO-K1 cells to 100 μM vanadyl alone induced significant (p < 0.05, one-way ANOVA with Dunnett’s T3 test) cytotoxicity compared to the control (cells treated with neither vanadyl nor selenite, Fig. 1). Treatment of cells only with selenite at concentrations of 0.1 and 0.5 μM seemed to slightly decrease cell damage compared to the control cultures, and the viability of cells exposed to 1 μM selenite was similar to the control. The three above-mentioned concentrations of selenite were regarded as non-cytotoxic. Importantly, the review of literature data revealed that cultured mammalian cells substantially differed in their sensitivity to selenite, as described hereafter. For instance, cultured human neuronal cells showed a viability decrease following exposure to selenite at doses as low as 0.1 μM (Maraldi et al. 2011). However, concentrations of selenite comparable to those used in our study were non-toxic to primary rabbit hepatocytes (Müller and Pallauf 2003), human hepatoma (HepG2) cells (Helmy et al. 2000), prostatic (PNT-1) cells (Maraldi et al. 2011), or human HaCaT keratinocytes (Hazane-Puch et al. 2013). Notably, human exposure to inorganic selenium via drinking water at concentrations similar to or much higher than those studied here have been documented in some regions of the world (reviewed by Vinceti et al. 2013a).Fig. 1

Bottom Line:
The effect of selenium applied as sodium selenite (Na2SeO3) on the cytotoxicity of vanadyl sulphate (VOSO4) was examined using CHO-K1 cells.Observations performed with a phase-contrast microscope showed most cells to be rounded upon treatment with VOSO4 alone.In turn, a majority of cells co-treated with VOSO4 and 1 μM Na2SeO3 were elongated, and exhibited cytoplasmic vacuolization.

ABSTRACTThe effect of selenium applied as sodium selenite (Na2SeO3) on the cytotoxicity of vanadyl sulphate (VOSO4) was examined using CHO-K1 cells. From the resazurin-based assay, it appears that Na2SeO3 at low doses (0.5 and 1 μM) can enhance 100 μM VOSO4-induced cell damage. The two-way ANOVA analysis revealed that the increased cell damage was a consequence of a synergistic interaction of 0.5 μM Na2SeO3 with VOSO4 and 1 μM Na2SeO3 with VOSO4. Observations performed with a phase-contrast microscope showed most cells to be rounded upon treatment with VOSO4 alone. In turn, a majority of cells co-treated with VOSO4 and 1 μM Na2SeO3 were elongated, and exhibited cytoplasmic vacuolization. These results warn of the potential contribution of inorganic selenium to vanadium-induced toxicity.